The present invention broadly relates to friction rail track brakes and pertains, more specifically, to a new and improved apparatus for engaging or activating and disengaging or deactivating a permanent-magnet slipper brake.
Generally speaking, the apparatus for engaging and disengaging a permanent-magnet slipper brake of the present development is of the type provided for a rail vehicle equipped with a pneumatic main line and a pneumatic feed line or conduit.
For engaging and disengaging a permanent-magnet slipper brake there are required relatively high forces which are generated or produced either by an electric motor or by a hydraulic motor.
On the one hand, for the braking operation, such a permanent-magnet slipper brake has to be lowered to the rails or rail tracks on which the vehicle is traveling. An example of such a magnetic device is shown in Braun, U.S. Pat. No. 3,493,086. This is generally pneumatically effected against the force of a spring which tends to lift the permanent-magnet slipper brake. On the other hand, a rotatable permanent magnet must be rotated or turned through approximately 90.degree. between two limbs or pole pieces, in order to direct the magnetic flux through the rails or rail tracks, whereby the permanent-magnet slipper brakes are attracted with full force toward the rails and the vehicle is fully braked. An example of such a rotatable magnet is shown in FIGS. 3 and 4 of British Pat. No. 721,748. For rotating or turning the permanent magnet between the pole pieces there are required the aforesaid relatively high forces which can be pneumatically applied only by cylinders and pistons of very large diameter.
However, it is difficult to provide such high forces by means of a pneumatic drive, without such pneumatic drive requiring a great deal of space.